A study of prehistoric animals has revealed the
crucial role of the English Channel in shaping the course of
Britain's natural history.
The Channel acted as a filter, letting some animals
in from mainland Europe, but not others. Even at times of low sea
level, when Britain was not an island, the Channel posed a major barrier
to colonisation. This was because a massive river system flowed along
its bed, according to UK researchers at a palaeo-conference in Gibraltar
Today the English Channel is 520km long, 30-160km wide,
about 30-100m in depth and slopes to the south-west. Even now, the bed
of the Channel is incised by a network of valleys, the remains of the
river system, which may have been cut by catastrophic drainage of
meltwater from further north.
'It would have been an incredible barrier at times of
high sea level, but it would also have been a formidable barrier at times
of low sea level for populations trying to move south to north,' said
Chris Stringer of London's Natural History Museum. Professor Stringer
presented the results here at the Calpe conference, a meeting of
prehistory experts from all over the world.
The big flood
The evidence comes from the Ancient Human Occupation
of Britain Project (AHOB). This five-year undertaking by some of the
UK's leading palaeo-scientists has reassessed a mass of scientific data
and filled in some large knowledge gaps with new discoveries. Chris
Stringer's co-researchers, Andy Currant, Danielle Shreve, and Roger
Jacobi, have been studying how the mammalian fauna of Britain has
changed over the last 500,000 years.
During that period, animals have colonised, abandoned,
and re-colonised Britain many times as the climate shifted from warm to
cold and back to warm. The Channel is thought to have formed during a
cold period 200,000 years ago or more. Meltwater from an ice sheet
formed a lake, which then overflowed in a catastrophic flood - cutting
through a chalk ridge that previously connected Britain to France.